The runes heal way too much

So I played a game against a Draven using Glacial augment, nothing new there. But one thing, and one thing only caught my attention. Draven with Vampiric scepter as his only lifesteal item healed over 460HP when critting a minion with a NORMAL basic attack. He didn't have an axe spinning.

Keep in mind, his team had no healers or anything of the sort and his three possible sources for healing were His vampiric scepter, Ravenous hunter and taste of blood. He didn't even have fleet footwork.

Now what the hell is going on here? In old times, Draven wouldn't have healed 1/3 of his max HP with just one basic attack. With only Vampiric (And the possible lifesteal runes and masteries) He would have to do easily over 3000 DMG to heal that much (10% From Vampiric and the rest from runes). Now he had to deal roughly 1000 dmg To heal the same amount. And again, he did not have an axe spinning, that was his normal basic attack.

Is this Just Draven or is it every other ADC too?